Liquid fuel injection pumps

ABSTRACT

A LIQUID FUEL INJECTION PUMP INCLUDING A TOOTHED COLLAR MOVABLE ANGULARLY TO VARY THE QUANTITY OF FUEL DELIVERED BY THE INJECTION PUMP, A RACK BAR HAVING A TOOTHED PORTION FOR ENGAGEMENT WITH THE TEETH OF THE COLLAR AND THERE IS PROVIDED AT THE OPPOSITE ENDS RESPECTIVELY OF THE TOOTHED PORTION OF THE RACK BAR, CURVED END FORMS WHICH ARE SHAPED TO ENGAGE WITH THE CRESTS OF A PLURALITY OF THE TEETH OF THE PINION TO LIMIT THE EXTENT OF AXIAL MOVEMENT OF THE RACK BAR.

March 2, 1971 P. F. CORNFOOT LIQUID FUEL INJECTION PUMPS Filed Feb. 27, 1969 N NT I? gga O ATT ENEYS United States Patent l 3,566,702 LIQUID FUEL INJECTION PUMPS Peter F. Cornfoot, Hucclecote, England, assignor to Bryce Berger Limited, Hucclecote, England Filed Feb. 27, 1969, Ser. No. 802,909 Claims priority, application Great Britain, Mar. 1, 1968,

0/68 Int. Cl. F16h 19/04; F02m 15/00 US. CI. 74-29 1 Claim ABSTRACT OF THE DISCLOSURE This invention relates to liquid fuel injection pumps for supplying fuel to internal combustion engines and of the kind comprising a plunger reciprocably accommodated within a bore formed in a body of the pump, a collar surrounding an exposed end portion of the plunger, means connecting the plunger and collar whereby angular movement of the collar will result in angular movement of the plunger whilst allowing relative axial movement therebetween, a pinion formed integrally with or secured to the collar, a rack bar slidable in the body, the teeth of said rack bar being engaged with the teeth of the pinion and stop means for limiting the extent of movement of the rack bar.

The object of the invention is to provide such a pump in a simple and convenient form.

According to the invention in a pump of the kind specified said stop means is defined by curved end forms disposed at the opposite ends of the toothed portion of the rack bar respectively said end forms being shaped to engage with the crests of a plurality of the teeth of the pinion.

In the accompanying drawings:

FIG. 1 is a sectional side elevation of one example of a liquid fuel injection pump in accordance with the invention, and

FIG. 2 is a plan view of part of the apparatus of FIG. 1.

In one example of a liquid fuel injection pump in accordance with the invention there is provided a body defined by upper and lower body portions 10, 11. Both these portions are of generally square form and the upper face of the lower body portion is provided with an annular rim 12 around which engages the upper body portion. The portions are retained relative to each other by four studs which are secured in the portion 11 and extend upwardly through the upper portion. Sleeve nuts are provided to engage the studs.

Defined in the body portion is a stepped bore 13 the stepped portion of which tapers inwardly from the wider to the narrower portion of the bore. Mounted within the bore is a pump barrel 14 which extends into the 'body portion 11 and which is flanged at its end within the upper body portion. The lower face of the flange is shaped in a manner complementary to that of the stepped portion of the bore and formed within the pump barrel is a cylindrical bore 15 in which is mounted a reciprocable pumping plunger 16.

Patented Mar. 2, 1971 ice The end of the bore 15 flares outwardly at the flanged end of the pumping barrel to receive a locating piece 17 which is shaped in a complementary manner. The locating piece is provided with a recess 18 to accommodate with clearance, and extension 19 formed on a delivery valve body 20. The delivery valve body is of cylindrical shape and is urged into contact with the locating piece 17 by means of a retaining member 21 which fits within the wider portion of the stepped bore. The retaining member is held in position by a retaining ring 22 which is secured to the upper body portion by means of nuts 23 which are engaged with the studs. When the aforesaid nuts are tightened the retaining ring 22 urges the retaining member 21 towards the pump barrel and the locating piece 17 together with the delivery valve body are clamped therebetween to form liquid tight seals.

The retaining member 21 is provided with a central aperture 24 through which fuel flows to an outlet union 25 from the bore in which the plunger is mounted and furthermore, the retaining member is provided with a stop 26 to limit the extent of movement of a spring loaded delivery valve element 27 which is located within a bore formed in the delivery valve body 20 and the extension 19. This bore is in communication with the bore 16 formed in the pump barrel. The delivery valve element is of the well known type and is guided for movement by fluted portions formed thereon.

The end portion of the pump barrel 14 which is situated within the body portion 11 is of reduced diameter and around this portion of the pump barrel is mounted a control sleeve 28 which extends beyond the end of the pump barrel. The upper portion of the sleeve is provided with teeth 29 defining a pinion for engagement with a rack bar 30 which is slidably mounted within the lower body portion. The sleeve 28 is retained in position by means of a spring abutment 31 which is urged by its associated coiled compression spring 32 against a surface defined in the lower body portion and a flange formed on the external periphery of the sleeve. The other end of the spring bears upon a spring abutment 33 carried by the end of the plunger. This spring abutment is secured to a tappet 34a which is slidable within the lower part of the lower body portion and which can be acted upon by a cam not shown. If desired the tappet may be replaced by a roller assembly.

The sleeve 28 is movable angularly by the rack bar 30 in order to determine the angular setting of the pumping plunger within the pump barrel. Connecting means is provided intermediate the sleeve and the plunger whereby angular movement of the sleeve will impart angular movement to the plunger at the same time permitting relative axial movement therebetween. The connection means comprises an axial slot which is formed at one point on the periphery of an enlarged portion 34 of the plunger and for co-operation with this slot there is a key 35 which is secured on the internal periphery of the sleeve. The key may be suitably shaped for close co-operation with the internal periphery of the sleeve as is shown or alternatively the sleeve may be provided with an axially extending recess in which the key is partly accommodated.

Formed in the pump barrel are a pair of oppositely disposed ports 36 which comunicate with an annular chamber 37 defined intermediate the pump barrel and the upper body portion. This chamber is in communication with a source of liquid fuel and opening into this chamber at a lower point is a spill port 38. During upward movement of the plunger 16 against the action of the coiled compression spring and when the various ports are covered by the plunger fuel is expelled past the delivery valve to the outlet. The termination of delivery of fuel in this manner is determined in a well known manner, by the opening of a helical groove not shown formed on the periphery of the plunger with the spill port. The helical groove is in communication with the pumping chamber defined by the portion of the bore intermediate the plunger and the delivery valve and when the groove is exposed to the spill port the fuel flows through the spill port into the aforesaid annular chamber. Since the fuel flows through this port at a very high rate a hardened erosion plug 39 is mounted in the upper portion of the body and extends into the aforesaid annular chamber at a position opposite the spill port so that the fuel leaving the latter impinges upon the plug. During downward movement of the plunger under the action of the coiled compression spring fuel flows into the pumping chamber when the ports 36 are uncovered by the end of the plunger.

In order to adjust the quantity of fuel which is delivered by the pump, the angular setting of the plunger is adjusted by means of the rack bar 30. It is necessary to provide stops on the rack bar whereby the extent of movement of same is limited. These stops are defined by curved end forms 40 which are formed at the opposite ends of the toothed portion of the rack bar 11 respectively. The end forms 40 are shaped to engage with the crests of a plurality of the teeth 29 of the pinion and in this manner a number of teeth are loaded when the rack bar is moved to its terminal positions.

The arrangement of the retaining member 21, the delivery valve body 20, the locating piece 17, the pump barrel 14 and the upper body portion 10 ensures that the pump barrel and that portion of the delivery valve body which accommodates the delivery valve are free from distortion due to the clamping force furthermore, the upper body portion and the lower body portion can be moved angularly relative to each other in order to suit the particular engine with which the pump is associated. A barrel locating screw 41 is conveniently provided in the upper body portion and this serves to locate the barrel prior to tightening of the nuts 23 which effect the clamp- 4 ing. The main clamping force is however developed over the whole length of the stud and between the annular retaining ring 22 and the lower body portion 11.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A liquid fuel injection pump for supplying fuel to internal combustion engines and of the kind comprising a pump body, a bore formed in the pump body, a plunger reciprocably accommodated within the bore, a collar surrounding an exposed end portion of the plunger, means connecting the plunger and collar whereby angular movement of the collar will result in angular movement of the plunger whilst allowing relative axial movement therebetween, a pinion mounted on the collar, a rack bar slidable in the body, a toothed portion on said rack bar and having teeth engaged with said pinion whereby axial movement of the rack bar will effect angular movement of the pinion, curved end forms disposed at the opposite ends of the toothed portion of the rack bar respectively, said end forms presenting concave surfaces to the pinion and serving to engage with the crests of a plurality of teeth of the pinion to constitute stop means to limit the extent of movement of the rack bar.

References Cited UNITED STATES PATENTS 2,704,035 3/1955 Bader 103-154 2,877,711 3/1959 Evans 103-154 2,953,992 9/1960 Bartholomaus et a1. 103-154 3,267,863 8/1966 Clifton 103-154 FOREIGN PATENTS 1,284,762 1/1962 France 103-154 843,046 8/1960 Great Britain 103-154 HENRY F. RADUAZO, Primary Examiner 

